Does the time from diagnostic biopsy to neoadjuvant chemotherapy affect the rate of pathologic complete response in stages I-III breast cancer?

Background: Studies in the adjuvant setting suggest that the timing of breast cancer diagnosis, surgery, and chemotherapy might affect outcomes. In the neoadjuvant setting, data exploring whether expeditious neoadjuvant chemotherapy (nac) after diagnosis improves the rate of pathologic complete response (pcr) in breast cancer are limited. Methods: Patients who received nac and completed treatment between May 2012 and December 2018 were identified from a prospectively collected database at BC Cancer. Time from diagnosis to start of nac was calculated. Patients were grouped into those who did and did not experience a pcr, and those who started nac within 28 days or after 28 days [time to nac (ttn)]. The association between pcr and ttn was tested using logistic regression. Results: In the time period studied, 482 patients who received nac were identified. After exclusions, 421 patients met the eligibility criteria. Median time from biopsy to chemotherapy was 33 days (range: 7-140 days). In 149 patients (35.4%), nac was received within 28 days of diagnosis (range: 7-28 days); in 272 patients (64.6%), it was received after more than 28 days (range: 29-140 days). The overall pcr rate was 31.8%. A trend toward a higher pcr rate, although not statistically significant, was observed in the group that initiated chemotherapy within 28 days (34.2% vs. 30.5%, Conclusions: In the neoadjuvant setting, we observed no difference in the rate of pcr in patients who started nac within 28 days or after 28 days.